The
extension is added to the names of files when no extension is
specified, as in:

$
fpt anova intab sumsq

or

INCLUDE
'windtab'

If
a file is read which has an extension which differs from the current
default, the corresponding output file name is constructed by
appending the extension to the base file name with a separating
underscore. For example, if the default primary input file name
extension is .for,
and the primary output file name extension is .FPT,
the input file ANOVA.F
is rewritten to ANOVA_F.FPT.
This behaviour is modified by the commandsKEEP FILE NAME EXTENSIONS and MAXIMUM BASE FILE NAME LENGTH.

Where
to use this command:

Operating
system command line

Yes

Configuration
file, config.fsp

Yes

Specification
(FSP) files, *.fsp

Yes

Interactively,
to FPT>
prompt:

No

Interactive
command files

No

Embedded
in the Fortran code

No

Default:

The
defaults are operating system dependent. Under VMS and Windows the
default extension is .FOR.
Under Linux and Unix it is .f
(Note that defaults may be changed in the configuration file).